What is the best way of finding out which escorts are working alone (as in not sharing an apartment with other escorts)?

I am uncomfortable going into a place with multiple women working in the same location from a law point of view as well as not wanting to bump into another punter at the same time etc..

Sending pm's or phoning to ask if they work alone could understandably make an escort nervous, so what is the best way to approach this?

Thanks!